// Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0

//! `Nibble` represents a four-bit unsigned integer.

#![forbid(unsafe_code)]
#![cfg_attr(all(feature = "mesalock_sgx", not(target_env = "sgx")), no_std)]
#![cfg_attr(all(target_env = "sgx", target_vendor = "mesalock"), feature(rustc_private))]

#[cfg(all(feature = "mesalock_sgx", not(target_env = "sgx")))]
#[macro_use]
extern crate sgx_tstd as std;

// #[cfg(feature = "fuzzing")]
// use proptest::prelude::*;
use serde::{Deserialize, Serialize};
use std::fmt;

#[derive(Clone, Copy, Debug, Hash, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize)]
pub struct Nibble(u8);

impl From<u8> for Nibble {
    fn from(nibble: u8) -> Self {
        assert!(nibble < 16, "Nibble out of range: {}", nibble);
        Self(nibble)
    }
}

impl From<Nibble> for u8 {
    fn from(nibble: Nibble) -> Self {
        nibble.0
    }
}

impl fmt::LowerHex for Nibble {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{:x}", self.0)
    }
}

// #[cfg(feature = "fuzzing")]
// impl Arbitrary for Nibble {
//     type Parameters = ();
//     type Strategy = BoxedStrategy<Self>;
//
//     fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
//         (0..16u8).prop_map(Self::from).boxed()
//     }
// }
